Syringe barrels contain, store, transfer and measure liquids, typically containing medicaments or other fluids for delivery to a patient. Medical devices, including plunger rods and stoppers, are used to aspirate and expel liquid from syringe barrels. During aspiration, air can become trapped within the syringe barrel. The presence of air within the syringe barrel can result in inaccurate dosage measurements and other issues.
Typically, air is removed from syringe barrels, by inverting the syringe barrel to force the air trapped within the barrel to the opening through which the fluid is aspirated. The air is then expelled through the opening by applying a force on the plunger rod in the distal direction. This expulsion process, however, can result in the expulsion of a portion of the liquid aspirated into the syringe barrel. In addition, this method of removing air from the syringe barrel may require the user to agitate the barrel of the syringe to force the air bubbles to move toward the opening.
Attempts to remove air from syringe barrels have included the use of a venting system to allow air to flow out of syringe barrels and other containers. Filters have been utilized to allow air to escape but prevent the desired liquid from also flowing out of the chamber of the barrel. Such attempts, however, rely on natural forces to passively cause a pressure differential across the filter to force air to permeate through the filter. In some instances, the filtering devices are part of a separate component that must be attached to the tip of syringes by the user prior to use of the syringe. There is a need to alleviate the need for users to actively remove air from syringe barrels and other containers before use.